In the case of a wide band wireless communication system, effective transmission/reception schemes and utilization schemes have been proposed in order to maximize the efficiency of limited radio resources. One of systems that are being taken into account in the next-generation wireless communication systems is a multi-carrier system. A multi-carrier system means a system for configuring a wide band by aggregating one or more carriers, each having a smaller bandwidth than a wide band, that is, a target, when a wireless communication system supports a wide band.
A conventional wireless communication system, such as 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), uses carriers having various bandwidths, but the system is a single carrier system using one carrier. In contrast, the next-generation wireless communication system, such as LTE-Advanced (LTE-A), can be a multi-carrier system using an aggregation of multiple carriers, that is, a Carrier Aggregation (CA).
In a single carrier system, for example, LTE, in uplink in which a mobile station transmits a signal to a base station, a single carrier characteristic is used to efficiently utilize the power amplifier of the mobile station. A mobile station uses a control region in which control information is transmitted and a data region in which data is transmitted separately and does not send signals in the control region and the data region at the same time in order to maintain the single carrier characteristic.
In contrast, in a multi-carrier system, for example, LTE-A, simultaneous transmission in the control region and the data region may be permitted or not permitted depending on a configuration. In a multi-carrier system, a mobile station may need to send both control information and data at a specific point of time even when simultaneous transmission in the control region and the data region is not permitted. In this case, the mobile station may send the control information and the data in the data region at the same time. This is said that the control information is piggybacked (or multiplexed) and transmitted.
In a multi-carrier system, if transmission in the data region using a plurality of carriers is scheduled at a point of time at which a mobile station must send control information, there is a problem in that whether the control information must be piggybacked on the data region of what carrier and transmitted is not clear.